Insulated shipping containers for food stuffs and other perishable items are usually stored during transit in a refrigerated compartment, such as the hold of a ship, or are provided with means, such as portable refrigeration units or compressed gaseous refrigerant for the introduction to the interior of the container of cooled air or refrigerant gas, to maintain the contents thereof at a desired temperature to avoid spoilage. It is therefore, necessary in the construction of such shipping containers to provide means for the introduction to the interior of the container of refrigerated ambient air or refrigerant gas to facilitate the exchange or movement of cooled air or gas within the interior spaces of the container. This maintains the temperature of the contents at the desired level and avoids the accumulation of stale air and unwanted gasses.
Various means have been provided in the past to accomplish such venting. However, the devices that have been so utilized have been inadequate and unsuitable in many instances. This is due to the fact that they are not adaptable for shipping containers of various sizes and wall thicknesses, are uneconomical to manufacture and install, and fail to provide adequate protection to prevent the pilfering of the shipping containers during transit. Moreover, the venting ports heretofore known have often been formed of material which is not, corrosive resistant and have not been designed to be adequately air-tight to prevent the entry of ambient air at times when such entry was undesirable. In addition, the known means have often been difficult to operate. Furthermore, and most importantly, existing venting ports have been fitted with closure devices that are adapted to be connected to an interior bulkhead of the container. Any movement of such bulkhead relative to the port, which is often experienced, causes an improper seal of the closure and thus unwanted leakage past the port.
There has, therefore, been a long felt need for a venting port adaptable for use on containers of various sizes, that is economical, easy to install and use, and adequately seals the container and vents the container at the desired times.